1. Field
Embodiments of the present disclosure relate to an electronic brake system, and more particularly, to an electronic brake system configured to perform in-circuit control for detecting a hydraulic circuit failure and preventing an accident and a control method thereof.
2. Description of the Related Art
Brake systems have to be installed for braking in vehicles, and recently, various types of systems have been proposed for obtaining more powerful and stable braking force.
Examples of the brake systems are an anti-lock brake system (ABS) configured to prevent wheels from slipping during breaking, a brake traction control system (BTCS) configured to prevent driving wheels from slipping when vehicles are suddenly or rapidly accelerated, and a vehicle attitude control (that is, electronic stability control (ESC)) system which combines the ABS and the BTCS to control brake hydraulic pressure and maintains a stable state for vehicle driving.
In general, an electronic brake system includes a hydraulic pressure supplier configured to receive a braking will of a driver as an electrical signal from a pedal displacement sensor configured to detect a displacement of a brake pedal when the driver steps on the brake pedal.
The hydraulic pressure supplier is provided to operate a motor according to a force applied to the brake pedal and generate a braking pressure. Here, the braking pressure is generated by converting a rotational force of the motor into a linear motion that presses a piston.
Active hydraulic booster (AHB) systems have recently been installed in vehicles such as hybrid cars, fuel cell cars, and electric cars.
In general, the AHB system is a brake system in which an electronic control unit (ECU) configured to perform overall control of the system when a driver stepping on a brake pedal is detected, generates a hydraulic pressure using a hydraulic power unit (HPU) configured to generate the hydraulic pressure using a motor, supplies the hydraulic pressure to a master cylinder, and generates a braking force by transmitting a braking hydraulic pressure to wheel cylinders of wheels using an ESC system configured to control a braking force of the wheels.
Such an AHB system generates a necessary pressure for braking through valve control when a driver brakes. Valves used for the valve control include apply valves configured to supply a hydraulic pressure to wheel cylinders, cut valves configured to maintain the supplied hydraulic pressure, release valves configured to discharge the hydraulic pressure supplied to the wheel cylinders, and simulation valves configured to generate a force applied to a brake pedal.
When the AHB system operates normally, the AHB system operates by receiving a brake pedal signal when a driver steps on a brake pedal, and the apply valve is opened according to the operation of the AHB system, a high pressure brake fluid filled in a high pressure accumulator passes through the apply valve and is supplied to a boost circuit (BC), and a pressure of the BC is increased. At this time, the cut valves are simultaneously blocked to maintain the brake pressure. In addition, when the simulation valve is opened, the hydraulic pressure in the master cylinder pushes a spring in a pedal simulator to generate a pedal simulator pressure corresponding to a reaction force of the brake pedal.
However, when a hydraulic circuit failure, such as a leak in the BC, occurs, there is a concern in that the HPU continuously generates a hydraulic pressure and supplies the hydraulic pressure to the master cylinder, and a dangerous situation in which a braking force is not generated due to lack of a brake fluid occurs when the pressure is exhausted.